Previously unknown manifestation of heavy atom effect on the NMR chemical shifts of β- and γ-protons initiated by the relativistic effects of the tellurium and selenium atoms has been investigated in the representative series of selenium- and tellurium-containing compounds. To approve the four-component density functional approach to be the appropriate tool for the investigation of the heavy atom on light atom effect (HALA), the benchmark calculations of the proton chemical shifts have been performed at the CCSD level using comprehensively chosen locally dense basis set with taking into account solvent, vibrational, and relativistic corrections. A good agreement with the experimental data was achieved. The magnitudes of the relativistic HALA corrections to β- and γ-proton chemical shifts were found to vary in a wide range, namely from −3.08 ppm for the γ-proton of methyltelluraldehyde to 14.51 ppm for β-proton in benzotelluraldehyde. 相似文献
Radio-frequency identification systems used for the remote diagnostics of diseases and contactless monitoring and assessment of human health are reviewed. The propagation of electromagnetic waves inside a biological medium and along interfaces between different media, as well as the problem of telemetry data acquisition from implanted systems or system on the human body surface using wireless sensors, is considered. Emphasis is on radio-frequency identification systems that use far-field electromagnetic radiation, since they are necessary in emergency situations to find injured people in hard-to-reach places and assess the state of emergency response workers. 相似文献
Synthetic chalcogen–phosphorus chemistry permanently makes new challenges to computational Nuclear Magnetic Resonance (NMR) spectroscopy, which has proven to be a powerful tool of structural analysis of chalcogen–phosphorus compounds. This paper reports on the calculations of one-bond 31P 77Se and 31P 125Te NMR spin–spin coupling constants (SSCCs) in the series of phosphine selenides and tellurides. The applicability of the combined computational approach to the one-bond 31P 77Se and 31P 125Te SSCCs, incorporating the composite nonrelativistic scheme, built of high-accuracy correlated SOPPA (CC2) and Coupled Cluster Single and Double (CCSD) methods and the Density Functional Theory (DFT) relativistic corrections (four-component level), was examined against the experiment and another scheme based on the four-component relativistic DFT method. A special J-oriented basis set (acv3z-J) for selenium and tellurium atoms, developed previously by the authors, was used throughout the NMR calculations in this work at the first time. The proposed computational methodologies (combined and ‘pure’) provided a reasonable accuracy for 31P 77Se and 31P 125Te SSCCs against experimental data, characterizing by the mean absolute percentage errors of about 4% and 1%, and 12% and 8% for selenium and tellurium species, respectively. The present study reports typical relativistic corrections to 77Se 31P and 125Te 31P SSCCs, calculated within the four-component DFT formalism for a broad series of tertiary phosphine selenides and tellurides with different substituents at phosphorus. 相似文献
The accuracy of model kinetic equations is analyzed using the exact moment solutions of the Boltzmann–Maxwell equation for homoenergetic affine flows of a monatomic gas of Maxwellian molecules in the absence of external forces. Solutions of the third-order kinetic-moment equations for homogeneous shear flow and one-dimensional homogeneous expansion-collapse flow are considered. The principal advantages of the domestic Shakhov and, especially, Larina–Rykov models are demonstrated. 相似文献
The Mössbauer studies on 57Fe nuclei in multiferroics BiFe1 – xCrxO3 (x = 0.05, 0.10, and 0.20) have been performed at room temperature. The multiferroics BiFe1 – xCrxO3 (x = 0.05, 0.10, and 0.20) with the rhombohedral R3c structure have been prepared by solid-state synthesis under high pressures. The effect of substitution of Cr cations for Fe cations on the spatial spin-modulated structure, and also hyperfine electrical and magnetic interactions of 57Fe nuclei has been studied. The substituted ferrites demonstrate an anharmonic modulated spin structure of cycloid type, in which iron atoms with different cation environments take part. The anharmonism parameter of the cycloid linearly increases from m = 0.10 at x = 0 to m = 0.78 ± 0.02 at x = 0.20. The constants of magnetic uniaxial anisotropy Ku are estimated at room temperature: Ku ≈ 0.36 × 106 erg/cm3 at x = 0 and Ku ≈ 4.22 × 106 erg/cm3 at x = 0.20. 相似文献
The most important limitation for boron neutron capture therapy of cancer is the selective accumulation of boron compounds in tumor tissues in significant quantities. In this paper, we describe the possibility to use magnetic Ni/Fe nanotubes as carriers for boron delivery. Carborane derivatives containing 10 and 21 boron atoms per molecule were immobilized on Ni/Fe nanotubes by covalent and ionic interactions. Magnetic properties of NTs were investigated by Mössbauer spectroscopy. Structure, element, chemical composition, and morphology of obtained magnetic nanotubes were studied by XRD, SEM-EDA, and FTIR spectroscopy. Results indicate success immobilization of carborane derivatives on Ni/Fe nanotubes and great potential to use them as carriers for boron neutron cancer therapy of cancer.
Catalytic activity was found for Rh3+complexes with O-alkyl-Salkyl thiocarbon-ates in the homogeneous hydrogénation of unsaturated compounds. Cyclic voltamperometry was used to detect the formation of rhodium hydride intermediates during the hydrogénation of alkenes in the presence of these complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2336–2338, October, 1989. 相似文献